That probably would have been considered a nice, clear day Back Then. You probably could have seen the mountains from at least 5 miles away.

Things had, in general, improved when I started commuting to frequent meetings in LA in the late 1990s (usually flying into Burbank, and getting downtown on Metrolink). But I did have one run to Ontario and meetings in Riverside where, largely but not entirely due to wildfires, I couldn't see the hills from less than a mile away. Definitely a shallow-breathing day, and the meetings were to kick off an air quality research project!

I need to dig through my old slides and try to find that pic I got of a SP switcher dragging a few cars in the median of I-10 in the late '60s. Metrolink and toll lanes are there now. The air on that trip (midwinter iirc; checking out potential colleges) was just horrible, and was cold enough in Pomona to ice the motel pool overnight. Nice and clear (but cold enough to make the old family Dodge stop producing heat) over Grapevine, then fog through the whole Valley on 99 (before I-5 was complete). The weather finally got decent again as we climbed over Altamont. We probably took the Dodge because the VW wouldn't have made it through that long a trip without some kind of failure (that's the way old Beetles were).